Balanced, high output, rapid rotation wind turbine (Weathervane multi-rotor windmill)

ABSTRACT

A multiplicity of horizontal axis rotors are coaxially attached, at spaced intervals, to an elongate driveshaft. This driveshaft with attached rotors is aimed, not directly into the wind, but at a slightly offset angle, allowing each rotor to encounter a wind stream having fresh wind, substantially undisturbed by upwind rotors, reducing wind shadow effects from rotor to rotor. That offset angle may be in the vertical plane, horizontal plane, or oblique. The shaft is held with rotational freedom at or near its midsection by a cantilevered bearing means, and drives a load, such as an electrical generator. This cantilevered bearing means, along with the rotor laden driveshaft which it supports, is allowed to pivot, as an entire unit, about the vertical axis of a supporting tower. Certain embodiments comprise an active aiming means, others are configured to have more wind resistance from a downwind section than an upwind section, and so are self-aiming, like a weathervane. Multiple driveshafts may be mounted on a single pivoting frame. Since the amount of wind a rotor can capture in relation to its mass is inversely proportional to diameter, multiple small rotors weigh less than an equivalent larger one. Smaller rotors also rotate faster than large rotors, more closely matching the required rpm of a generator, reducing or eliminating the need for ratio gearing. A faster rotating shaft transmits the same power at less torque, and so may be less robust. This wind turbine is therefore lighter, faster, and simpler than prior art designs.

[0001] (This patent application is a continuation in part of U.S. patentapplication Ser. No. 09/881,511 (Filing Date Jun. 14, 2001))

BACKGROUND

[0002] This invention relates to wind turbines.

[0003] Prior Art

[0004] Conventional horizontal axis wind turbines suffer from certaindrawbacks, some of which are:

[0005] 1. High Mass of Large Rotors:

[0006] The mass of a rotor increases as function of the diameter cubed,while the swept area only increases as a function of the diametersquared. The amount of wind captured, per unit rotor mass, is thereforeinversely proportional to rotor diameter. The single large rotorcaptures less wind per unit mass than a plurality of smaller rotorssweeping an equivalent area would. Such a single, large, heavy rotoralso mandates the use of a commensurately stronger drivetrain and towerto support its ponderous weight.

[0007] 2. Slow Rotation Rate of Large Rotors:

[0008] Today's windmills, with their single large, slowly turning rotorrequire either a specially built, slow-speed alternator or generator, ora transmission means providing ratio gearing, such as a gearbox, tobring the rotation rate up to a speed compatible with a generator.Either solution is complicated, expensive, and heavy, adding to the costof the installation, as well as the strength required of the supportingtower.

[0009] For a given wind speed, the tip speed of similarly shaped rotorsis substantially the same, regardless of diameter. The rotational rateis therefore inversely proportional to rotor diameter, meaning that asmaller rotor spins faster to maintain the same tip speed as a larger,more slowly rotating set of blades. Conventional generators andalternators typically require such a fast rotation rate for efficientoperation. Small rotors, turning more quickly, can therefore oftendirectly drive a substantially standard alternator or generator withoutratio gearing, or a transmission. With smaller rotors, if a transmissionis required, it need incorporate less ratio gearing, and may thereforebe less substantial, since the rotational rate of a smaller rotor isfaster to begin with.

[0010] 3. Faster Rotation Delivers the Same Power at Lower Torque:

[0011] A given amount of power is delivered at lower torque by a fasterrotating shaft, further reducing the required robustness, and thereforethe cost and weight, of the drivetrain.

[0012] 4. Low Power Output from Smaller Rotors in Prior Art:

[0013] Though smaller rotors are desirable from the standpoint ofachieving a higher rotation rate, the amount of wind power availablefrom the area swept by a smaller rotor is less than that of a largerrotor, being proportional to the diameter squared. Conventionalwindmills having a single small rotor therefore require high winds foruseful amounts of energy to be generated.

[0014] Many schemes have been put forward in the prior art tomechanically harness a multiplicity of smaller rotors together to powera single load. None has proven to be simple and reliable enough to haveenjoyed commercial success. Prior art designs utilizing a multiplicityof rotors coupled to a single shaft disposed these rotors closelytogether, and directly in line with the wind, and had no means forsupplying fresh wind to each rotor, and therefore suffered fromexcessive wind shadow effects between rotors, making the redundancy ofmultiple rotors largely ineffective, non-advantageous, and indeed,burdensome and unworkable.

[0015] 5. A dedicated azimuthal orientation means is normally requiredto keep a conventional upwind rotor properly aimed into the wind. Thisdirectional orientation means normally comprises either downwind fluidreaction surfaces, such as a tail fin, or an active directional controlmechanism. Either solution adds extra cost, weight, wind resistance, andcomplication to an installation, while not otherwise contributing topower generation.

[0016] 6. Safety Issues: It is possible for virtually any wind turbineto undergo structural failure at some point in its service life. Withtip speeds often exceeding 150 mph (˜mach 0.2), the ponderously largeblades of conventional wind turbines store a tremendous amount ofkinetic energy, and are known to be very dangerous if broken ordetached, even in home installations. These huge rotor blades, (with amass proportional to the diameter cubed, even though the power collectedis only proportional to the diameter squared) often require a heavy-dutycrane to be lifted into place. On the average one person dies every yearin such operations.

[0017] 7. Vibration issues: Prior art turbines are known to transmit lowfrequency vibration to structures upon which they are mounted, oftenmaking rooftop mounting inadvisable.

[0018] 8. Noise issues: Conventional windmills with a single rotor oftenproduce noise in high winds, which may be objectional in residentialareas.

[0019] The invention presented in U.S. patent application Ser. No.09/881,511 by this inventor addresses and solves these drawbacks ofprior art. That invention as disclosed, in several of its mainembodiments, places a multiplicity of substantially conventionalhorizontal axis rotors at spaced intervals along a single, semi-flexibletower/driveshaft. This tower/driveshaft protrudes from its base into thewindstream, naturally bending downwind to properly orient the rotors forpower generation. The entire structure is caused to spin along itslongitudinal axis, transmitting useful power to the base using only asingle moving part. The coupling of multiple rotors achieves a high rateof rotation, with more total power than single rotor designs. This highpower is delivered at a fast rate of rotation, and therefore at lowtorque, allowing the shaft to be less substantial than it would need tobe to deliver the same power at a slower rate of rotation. The presentinvention addresses two challenges inherent in this previous design, asdisclosed by this inventor:

[0020] 1. Stress on the Tower/Driveshaft:

[0021] In certain embodiments, the tower/driveshaft of this previouslydisclosed invention protrudes substantially perpendicular to the winddirection, and must then bend downwind to properly orient the rotors.This tower/driveshaft must support the weight of the rotors, resist theforce of the wind thereupon, and transmit the rotational torquegenerated thereby to the base, all while spinning about its longitudinalaxis, while in a bent configuration. This transmission of torque by ashaft that is both spinning and bent under load is very stressful to theshaft.

[0022] 2. Stress on the Cantilevered Bearing Means:

[0023] The downwind forces exerted on the multiple rotors and theirsupporting tower/driveshaft, by the wind, and by their weight, astransmitted through the leverage afforded by the length of thetower/driveshaft, result in large radial loading upon the bearings ofthe cantilevered bearing means at the base.

BRIEF SUMMARY OF THE INVENTION

[0024] The present invention is a modified, more balanced version of theinvention disclosed in U.S. patent application Ser. No. 09/881,511. Inthat disclosure, the rotating tower/driveshaft served to elevate therotors, and bent downwind to properly orient them. The present inventionretains the support, such as a stationary tower, of a conventional windturbine, while nonetheless preserving several of the advantages of theembodiments disclosed in U.S. patent application Ser. No. 09/881,511.

[0025] In this new, more balanced version, the driveshaft extends bothforward, substantially into the direction of the wind, as well asbackward, or substantially downwind. This more balanced configurationinvolves less leverage, and results in less stress on the cantileveredbearing means, less stress on the shaft, as well as requiring lessbending of the shaft. The entire assembly is mounted on a conventionalsupport means, such as a tower, building, tree, pole, or other elevatingstructure. Since the shaft protrudes in two directions from thecantilevered bearing means, the stress on the shaft is automatically cutat least in half. Since no part of the driveshaft is acting as thetower, leverage and stresses on the shaft are further reduced. And sincethe length of shaft presented is more parallel to the wind, bendingstresses on the shaft are even further dramatically reduced.

[0026] The direction of projection of the shaft, while having a majorcomponent substantially parallel to the wind, may be offset from theactual wind direction in an amount sufficient to allow an intermixtureof fresh, undisturbed wind into the disk swept by each succeeding rotor,so that each rotor may effectively harness wind energy without unduedisturbance from upwind rotors, and substantially contribute toward theoverall rotation of the shaft.

[0027] Some advantages of the embodiments of the previously disclosedinvention, in common with the invention disclosed herein are:

[0028] 1. Lighter rotor weight:

[0029] A multiplicity of smaller rotors weighs less than a single largerrotor sweeping an equivalent total area. This is because the mass of arotor is proportional to the third power of the diameter (diametercubed), while the area swept is only proportional to the second power ofthe diameter, (diameter squared). The larger the rotor, the less wind itcan capture relative to its mass.

[0030] 2. Faster rotation:

[0031] For a given rotor type, in a given wind speed, the tip speed isbasically some multiple of the wind speed, independent of rotordiameter. Therefore, smaller rotors rotate at a faster rate (rpm) thanlarger rotors. The multiplicity of smaller rotors of the presentinvention has a faster rate of rotation (rpm) than a single larger rotorof equivalent swept area. Since electrical generators perform best atsuch a relatively high rate of rotation (rpm), the present inventionmore closely matches the desired rotation rate (rpm) of currentelectrical generating equipment. This means that a gearbox is either notneeded, or, if needed, may be less substantial than would be the casewith a single, large, slowly spinning rotor with its commensurate hightorque. One version of the present invention even takes advantage ofcounter-rotating sets of rotors, and their differential relative rate ofrotation, which essentially doubles the effective rate of rotation.

[0032] 3. Lighter Duty Drivetrain:

[0033] A faster-rotating driveshaft can transmit the same power at lesstorque than a more slowly rotating driveshaft. Since the presentinvention rotates faster, torques are lower, requiring a lesssubstantial drivetrain. This lowers cost, as well as further loweringoverall weight.

[0034] 4. Self-Aiming Behavior:

[0035] The previously disclosed invention was a downwind machine.

[0036] The present invention, can easily be configured as aself-orienting, semi-downwind machine, either by having more rotorsdownwind than upwind of an azimuthal pivot point, or by giving thedownwind rotors more leverage, spaced further from the pivot point, sothat the windmill naturally points into the wind, in the fashion of aweathervane.

[0037] 5. Safety:

[0038] Multiple smaller rotors store less kinetic energy than equivalentlarger ones. This translates to less danger should mechanical failureoccur.

[0039] 6. Vibration:

[0040] The low frequency vibrations associated with larger rotors arereduced or eliminated with multiple smaller rotors, making rooftopinstallations more practical.

[0041] 7. Noise:

[0042] The multiple small rotors will have different noisecharacteristics, in high winds, than single larger ones, and maytherefore be less objectionable to nearby residents.

[0043] Some advantages that the embodiments disclosed herein have overthe previously disclosed embodiments of U.S. patent application Ser. No.09/881,511 are:

[0044] 1. Since the shaft protrudes in two directions from thecantilevered bearing means, the stress on the shaft is automatically cutat least in half in the present invention.

[0045] 2. Since no part of the driveshaft is acting as the tower, theoverall length of the shaft, as well as leverage and stresses on theshaft are further reduced.

[0046] 3. Since the length of shaft presented is more parallel to thewind, bending stresses on the shaft are even further dramaticallyreduced, because the wind has less leverage.

[0047] 4. The radial loads on the bearings are dramatically reduced,since the windmill is largely balanced about the bearings, since thedriveshaft protrudes therefrom in both directions.

[0048] Some disadvantages associated with this new design are:

[0049] 1. We give up the “single moving part” of the previous design,assuming that the present invention is mounted with directional freedom.

[0050] 2. We must use a conventional elevated mount, such as a tower.

[0051] 3. We give up having the load located at ground level.

[0052] 4. We give up having a non-rotating load—that is, in this case,the orientation of the load changes depending on wind direction, meaningthat a simple power cable from the load to the ground could eventuallybecome twisted too far in one direction, so accommodations must be madefor that fact; a means, such as slip rings, or a cable that can beunplugged, untwisted, then re-plugged in, must be used for transmittingpower to the ground, unless the installation happens to be in a locationwhere the wind never changes direction, or the installation ishard-mounted in a certain direction, or an active aiming mechanism isused, so that the cable may be untwisted at will automatically byrotating the orientation of the assembly on the tower.

[0053] Nevertheless, as every design involves tradeoffs, for manyapplications the embodiments of the present invention do indeed exhibitsuperior cost and performance characteristics overall.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0054]FIG. 1 Shows an oblique side view of a passively aimed windturbine installation of the tenth embodiment, having a streamlinednacelle, and a streamlined mounting pylon.

[0055]FIG. 2 Shows a closeup view of the streamlined nacelle of thetenth embodiment.

[0056]FIG. 3 Shows an oblique front view of a version of the tenthembodiment having two-bladed rotors, sequentially offset at 90 degrees.

[0057]FIG. 4 Shows a side view of the tenth embodiment, and attempts todepict the flow of fresh wind to each rotor, by virtue of the distancebetween rotors, and the offset angle of the driveshaft from the winddirection.

[0058]FIG. 5 Shows an oblique side view of the eleventh embodiment,wherein the tower 90 is split into two sections, an upper section and alower one. The upper section of tower is offset and rotates, making thisa passively aimed, downwind machine.

[0059]FIG. 6 Shows a closeup view of the streamlined nacelle of theninth embodiment, mounted atop a streamlined pylon, which is itselfmounted atop a turntable type pivot.

[0060]FIG. 7 Shows an oblique side view of a passively aimed windturbine installation of the first embodiment.

[0061]FIG. 8 Shows a closeup view of the cantilevered bearing means,load, and azimuthal orientation means of the first embodiment, asmounted atop a tower.

[0062]FIG. 9 Shows an oblique side view of a passively aimed windturbine installation of the second embodiment, with counterweightedupwind section of the driveshaft.

[0063]FIG. 10 Shows a closeup view of the cantilevered bearing means,load, resilient elevation angle control means, and azimuthal orientationmeans of the second embodiment, as mounted atop a tower.

[0064]FIG. 11 Shows an oblique side view of an actively aimed windturbine installation of the third embodiment.

[0065]FIG. 12 Shows a closeup view of the cantilevered bearing means,load, actively controlled elevation angle control means, and activelycontrolled azimuthal orientation means of the third embodiment, asmounted atop a tower.

[0066]FIG. 13 Shows an oblique side view of a passively aimed windturbine installation of the fourth embodiment, featuring a dedicateddownwind offset extension means.

[0067]FIG. 14 Shows an oblique side view of a passively aimed windturbine installation of the fifth embodiment, with counter-rotatingrotors driving two counter-rotating halves of the driveshaft, drivingtwo counter-rotating halves of a load.

[0068]FIG. 15 Shows a closeup view of the cantilevered bearing means ofthe fifth embodiment, with two counter-rotating halves of the load, asmounted atop a tower.

[0069]FIG. 16 Shows an oblique front view of the passively aimed windturbine installation of the sixth embodiment, having two driveshaftswith attached rotors, mounted to a single pivoting frame.

[0070]FIG. 17 Shows an oblique front view of the balanced, activelyaimed wind turbine installation of the seventh embodiment, having ahorizontal driveshaft with attached rotors, with an offset angle in thehorizontal plane.

[0071]FIG. 18 Shows an oblique front view of the passively aimed windturbine installation of the eighth embodiment, having a horizontaldriveshaft with attached rotors, with an offset angle in the horizontalplane, as determined by a fluid reactive offset angle inducing means.

PART NUMBERS IN THE DRAWING FIGURES

[0072]4 bearing support means

[0073]5 cantilevered bearing means

[0074]6 load

[0075]10 elongate driveshaft

[0076]11 bearing

[0077]13 horizontal axis type rotor

[0078]15 axle

[0079]27 resilient spring means

[0080]34 damping means (shock absorber)

[0081]35 horizontally rotatable azimuthal directional orientation means

[0082]36 elevation angle control means

[0083]37 lifting mechanism

[0084]38 pivot means

[0085]49 upwind section of the driveshaft

[0086]50 downwind section of the driveshaft

[0087]67 ballast counterweight means

[0088]90 tower means

[0089]91 outer rotating half of load 6

[0090]92 inner rotating half of load 6 (turns in opposite direction of91)

[0091]93 supporting armature means

[0092]94 fluid reactive offset angle inducing means

[0093]95 downwind offset extension means

[0094]96 active azimuthal directional orientation control means

[0095]97 streamlined mounting pylon

[0096]98 streamlined nacelle

[0097] A horizontal distance that the driveshaft projects upwind

[0098] B horizontal distance that the driveshaft projects downwind ifdifferent from A

[0099] α offset angle from wind direction, (becomes simply the elevationangle if the angular et is solely from the horizontal)

DETAILED DESCRIPTION OF THE INVENTION

[0100] 1. First Embodiment, FIGS. 7 and 8:

[0101] A plurality of substantially horizontal axis type rotors 13 arecoaxially mounted, at spaced intervals, along an elongate driveshaft 10.The driveshaft is substantially aligned with the wind, but at an offsetangle α, to allow each rotor to encounter at least some airflowsubstantially undisturbed by upwind rotors, as illustrated in FIG. 4. Inthis case the offset angle α is in the vertical plane. The driveshaftprotrudes in a freely rotating manner from each end of a cantileveredbearing means 5, and drives a load 6, mounted thereto. Thisdriveshaft/bearing/load combination is aimed into the wind much like aweather vane, being mounted on a horizontally rotatable azimuthaldirectional orientation means 35, which is in this case essentially ahorizontally rotatable pivot, that functions like a turntable. In thisembodiment there are five rotors mounted on the downwind section 50 ofthe driveshaft, and only four rotors along the upwind section 49 of thedriveshaft. The horizontal distance B that the driveshaft projectsdownwind is also substantially greater than the horizontal distance Athat the driveshaft projects upwind. (Note that foreshortening in theperspective view of FIG. 6, may affect the viewer's casual perception ofthis difference in length, making it appear to be less than it is. Atrue side view of a similar turbine is seen in FIG. 4)

[0102] The longer end of the driveshaft with five rotors is blowndownwind because:

[0103] Five rotors present more wind resistance than four.

[0104] The longer end with five rotors also has more leverage. (Thisextra length of the downwind section of the driveshaft comprises adownwind offset extension means 95.)

[0105] The downwind rotors also are higher than upwind rotors, andtherefore encounter the higher wind speeds found at higher altitude, andare therefore more forcefully blown downwind thereby.

[0106] The operative principle is not the exact number of rotors, northeir exact distance upwind or downwind, but the fact that somepredominance of downwind rotors, in sheer number and/or the leveragethat they exert, and/or the extra force exerted upon them by virtue ofhigher altitude, will produce automatic downwind orientation behavior,in the fashion of a weathervane.

[0107] The cantilevered bearing means 5 is mounted atop the horizontallyrotatable azimuthal directional orientation means (horizontal pivot) 35at a slope, or offset angle α from the horizontal plane, as determinedby an elevation angle control means 36, which in this case is awedge-shaped support, and is naturally guided by the wind to a positionazimuthally substantially aligned with the wind. The entire assembly ismounted atop an elevated support means, such as the conventional towermeans 90 of the drawing figures.

[0108] The nose, or upwind section 49 of the driveshaft, extendingsubstantially into the wind, also points slightly downward, toward theground, at offset angle α from the horizontal plane. The tail, ordownwind section 50 of the driveshaft is blown, and caused to be aimed,substantially downwind, and yet projects slightly upward, toward thesky, at offset angle α from the horizontal plane, as well. The rotorsare separated sufficiently that, with the shaft projecting at an offsetangle α from the wind direction, there is sufficient distance from onerotor to the next to allow at least a substantial portion of each rotordisk substantial access to a relatively undisturbed airflow. In otherwords, the shaft is tilted enough to significantly reduce wind shadoweffects from one rotor to the next, but not so much that the rotorscease to function efficiently, with enough distance between the rotorsto facilitate such an optimal zone of behavior. This offset angle α isin the vertical plane, in this case. The cantilevered bearing means 5 iscomprised of two bearings 11, and a bearing support means 4 (shown hereas a simple tube, in a cutaway view). An axle 15 freely rotates withinthe bearings, and supports the driveshaft 10. This assembly may befashioned, for example, with the axle 15 being hollow, and thedriveshaft inserted therein. The driveshaft may even extend completelytherethrough, in an uninterrupted fashion. The driveshaft may also besufficiently robust to be directly mounted in the bearings, withoutbeing held by an axle; indeed as the two may be fashioned as a singleunit, there need not be any distinction between them.

[0109] The offset angle α need not be exclusively in the vertical plane.An offset in the horizontal plane, or at an oblique angle, or even nooffset angle at all, are also possible within the scope of the presentinvention. Indeed, the aim of such a vertically slanted turbine may tendto naturally drift to one side, resulting in just such an oblique angle.

[0110] The load 6 is shown as an electrical generator, but couldcomprise any mechanical load.

[0111] This wind turbine weighs less than prior art turbines, androtates faster, due to having smaller rotors. The faster rotation lowerstorque, and eliminates or reduces the need for ratio gearing, furtherreducing weight and cost.

[0112] Since wind shadow effects increase with increasing wind speed,upwind rotors will partially shield downwind rotors in excessively highwinds, helping to prevent damage.

[0113] The downwind section 50 may additionally bend in higher winds,further aligning the rotors with the wind, and shielding downwindrotors.

[0114] If the offset angle α is reduced so as to be substantially equalto zero, then the amount of fresh wind encountered by each rotor isreduced to that amount allowed to enter the stream by virtue of thedistance between rotors. This lowers the available power but may protectthe turbine in excessively high winds.

[0115] While the rotors illustrated have three blades, other numbers ofblades are permissible, within the scope of the present invention. Forexample the turbine of FIG. 3 has two-bladed rotors, sequentially offsetby 90 degrees. This principle is true of all embodiments disclosedherein; any reasonable number of blades per rotor is possible, althoughtwo or three blades are well known in the art to be able to extract mostof the available energy in a windstream. Typically, the faster thedesired rate of rotation, the fewer blades per rotor are called for.

[0116] 2. Second Embodiment, FIGS. 9 and 10:

[0117] The second embodiment is similar to the first embodiment, butwith the downwind section 50 of the driveshaft being much longer thanthe upwind section 49 of the driveshaft, so that the downwind distance Bis much greater than the upwind distance A. There are also many morerotors mounted along this longer downwind section. The weight of theseadditional rotors, and this extra length of shaft, as amplified by theleverage afforded by this additional length, are at least partiallycounterbalanced by a ballast counterweight 67, mounted to the upwindsection 49 of the driveshaft. It should be noted that the upwind section49, being pointed into the wind, may be constructed more robustly thanthe downwind section. Such stronger construction may be sufficientlyheavy to act as a counterweight by itself, without the addition of adedicated weight.

[0118] The horizontal, or azimuthal component of the aim, is againcontrolled by the natural force of the wind causing lateral rotation ofthe cantilevered bearing means 5 and its projecting driveshaft 10 abouthorizontally rotatable azimuthal directional orientation means 35 (ahorizontally rotatable pivot), upon which the cantilevered bearing means5 is itself supported. The extra downwind length of the driveshaftcomprises a downwind offset extension means 95, which causes thispassively oriented turbine to be aimed into the wind in the fashion of aweathervane. The vertical component, or elevation angle, is controlledby an elevation angle control means 36, which in this case comprises alifting mechanism 37, that supports the upper end of the bearing supportmeans 4, the tubular enclosure that securely retains the bearings. Thistubular bearing support means 4 pivots about a pivot means 38 at itslower end. The action of this elevation angle control means 36 may beresilient in nature, and/or may be actively controlled, and/or may beconfigured to have a shock absorbing action. The lifting mechanismchosen for this embodiment comprises a resilient spring means 27, asmoderated by a damping means 34 such as a shock absorber. In excessivelystrong winds the downwind section is blown further downwind, rotating itlower, so that the spring is compressed. The action of this protectivemechanism places the rotors more in line with the wind, so that theytend to shield one another from the full force of the wind, preventingoverspeed, and thereby limiting damage from high winds.

[0119] The elevation angle control means 36 may be so configured thatthe action of this elevation angle control means 36 may comprise one ormore of the following:

[0120] The action may be elastic, or resilient in nature, with liftingmechanism 37 configured to have the action of a spring, with suchresilient mechanisms being well known in the art of machinery.

[0121] The action may be actively controlled, with lifting mechanism 37having features or properties known in the art that allow it to beactively adjusted.

[0122] It may also be configured to have a dampening, or shock absorbingaction, many mechanisms for which are also known in the art.

[0123] It may be configured to simply have no movement in the verticalplane, that is a static arrangement, at some constant offset angle, asin the first embodiment.

[0124] It may be configured to remain at a constant angle, but beadjustable.

[0125] The counterweight may be eliminated, at the expense of increasedradial loading on the bearings, and increased stress on the elevationangle control means.

[0126] The exact lifting mechanism 37 and pivot 38 shown are exemplaryonly, serving to illustrate the point that elevational aim may beinfluenced in general. Many simple alternative mechanisms known in theart may be adapted to comprise the elevation angle control means 36.

[0127] 3. Third Embodiment, Balanced Configuration, Active ElevationAngle Control Means, Active Azimuthal Angle Control Means; FIGS. 11 and12:

[0128] The Third Embodiment is similar to the First and SecondEmbodiments, except that it has an equal number of upwind rotors anddownwind rotors. The horizontal distance A that the driveshaft projectsdownwind is substantially equal to the horizontal distance A that itprojects upwind. This is not a downwind machine, nor an upwind machine,but a perfectly balanced wind turbine; Rather than being automaticallysteered by the wind, it is provided with directional control. In thiscase the direction of azimuthal directional orientation means 35 isactively controlled by active azimuthal directional orientation controlmeans 96, illustrated here as a simple gear drive. Many means for suchactive directional control are well known in the art. The elevationangle is also actively controlled by elevation angle control means 36,here, as in the previous embodiments comprising a lifting mechanism 37,that supports the upper end of the bearing support means 4, the tubularenclosure that securely retains the bearings. This tubular bearingsupport means 4 pivots about a pivot means 38 at its lower end. Thelifting mechanism 37, being actively controlled in this embodiment, isgraphically represented as a simple gear drive unit.

[0129] An advantage of this embodiment over the first two embodiments isreduced radial loading on the bearings, since the driveshaft is wellbalanced thereabout.

[0130] A further advantage is that power may be transmitted to groundlevel by a simple cable, rather than slip rings, since the activeazimuthal directional orientation control means 96 can be used to keep apower cable from becoming excessively twisted in one direction.

[0131] This arrangement is capable of generating an offset angle α ineither the vertical plane, the horizontal plane, or obliquely, by acombination of horizontal and vertical adjustment.

[0132] 4. Fourth Embodiment: Balanced Mounting Downwind of AzimuthalPivot; FIG. 13:

[0133] As in the previous embodiment, the upwind and downwind portions49, 50 of the driveshaft 10 are of equal length, with an equal number ofupwind and downwind rotors 13, so that the driveshaft and attachedrotors are balanced about the bearings, reducing radial loadingthereupon. Here, the cantilevered bearing means 5 and elevation anglecontrol means 36 are mounted to downwind offset extension means 95,which acts to support them downwind of horizontally rotatable azimuthaldirectional orientation means 35, about which this entire assemblypivots in the horizontal plane. Distance B, that the driveshaft projectsdownwind from the center of rotation of horizontally rotatable azimuthaldirectional orientation means 35, is greater than distance A that itprojects upwind, due to the downwind horizontal projection of downwindoffset extension means 95. The assembly is naturally blown downwind ofthe pivot point. This is, therefore, a downwind, passively orientedmachine, even though the driveshaft 10 projects in equal distancesupwind, and downwind, from the cantilevered bearing means 5.

[0134] The horizontally rotatable azimuthal directional orientationmeans 35 can be located at any height on the tower, with the towerdivided into two sections, above and below, the upper section coaxiallypivoting atop the lower section. In this case the upper section of thetower may even bend or project to one side, and thereby be coincidentwith downwind offset extension means 95, as in the eleventh embodiment,illustrated in FIG. 5.

[0135] The horizontally rotatable azimuthal directional orientationmeans 35 may also be located at the bottom of the tower, within thescope of this embodiment, so that the entire installation, includingtower, rotates as a unit.

[0136] An advantage that this embodiment shares with the thirdembodiment over the first two embodiments is reduced radial loading onthe bearings, since the driveshaft is well balanced thereabout.

[0137] An advantage of this embodiment over the third embodiment is thatit is a downwind machine, passively aimed, requiring no activedirectional control.

[0138] 5. Fifth Embodiment: Counter-Rotating, Balanced, DownwindMounting; FIGS. 14, 15:

[0139] The driveshaft is physically divided into two counter-rotatinghalves, the upwind half 49, and the downwind half 50. The upwind halfrotates clockwise as seen from downwind, and the downwind half rotatescounterclockwise. In FIG. 15 we can see that the load 6 is also dividedinto counterrotating halves, an outer half 91, which, being driven bythe upwind section 49 of the driveshaft, rotates clockwise, and an innerhalf 92 which rotates counterclockwise with the downwind section 50 ofthe driveshaft. It is easy to see that the effective relative rate ofrotation of the two halves 91, 92 of the load is approximately doubledby this counterrotation. This faster rate of relative rotation isdesirable from the standpoint that electricity is more readily generatedby most contemporary alternators and generators at such a fasterrotation rate, with gearboxes usually being employed to achieve such afaster rate. There are two separate cantilevered bearing means 5 withinthe single bearing support means 4, supporting two separatecounter-rotating axles 15.

[0140] As in the previous embodiment, while the driveshafts, inaggregate, are balanced about the bearing support means 4, the entireassembly is shifted downwind of horizontally rotatable azimuthaldirectional orientation means 35 (the horizontally rotatable pivot).Here, the elongate, tubular, bearing support means 4, being mounted toelevation angle control means 36 in an offset manner, serves thefunction of downwind offset extension means 95, and is so labeled. Suchan offset configuration is passively self-aiming, even though the upwindsection 49 and the downwind section 50 of the driveshaft are the samelength, with an equal number of rotors upwind and downwind.

[0141] An advantage of this embodiment is a faster effective relativerotation rate of the load, since it is divided into counter-rotatinghalves.

[0142] A disadvantage is increased radial loading on the bearings, sinceeach half of the driveshaft is supported in a fully cantilevered mannertherefrom, rather than being balanced as a single unit about thebearings.

[0143]6. Sixth Embodiment: Multiple Driveshafts Mounted on a RotatingFrame; FIG. 16:

[0144] This embodiment is similar to the first embodiment, except thatin this embodiment, a multiplicity of separate driveshafts, hereillustrated as two, are supported upon a rotating frame comprisingsupporting armature means 93. Here each driveshaft 10 has more downwindrotors than upwind rotors, as in the first embodiment, making this apassively oriented downwind machine. The extra length of each downwindsection 50 of the driveshafts 10 comprise downwind offset extensionmeans 95, which causes this machine to aim itself into the wind in themanner of a weathervane.

[0145] This same passively oriented downwind behavior can also beaccomplished with perfectly balanced driveshafts, having the same numberof upwind and downwind rotors, if the supporting armature means 93comprises a downwind offset extension means 95, such as disclosed in thefourth embodiment.

[0146] As illustrated, each driveshaft powers its own separate load,although the rotation of both driveshafts may alternatively bemechanically coupled to drive a single load, within the scope of thisembodiment. Means for such mechanical coupling are well known in the artof machinery.

[0147] The two driveshafts with their attached rotors may be configuredto counterrotate. This eliminates any residual torque imbalances in themachine.

[0148] A number, different than two, of separate driveshafts 10 may besupported by the supporting armature means 93, within the scope of thisembodiment.

[0149] 7. Seventh Embodiment: Balanced Driveshaft with Active AzimuthalControl, Offset Angle α is in the Horizontal Plane; FIG. 17:

[0150] In the seventh embodiment, the cantilevered bearing means anddriveshaft are mounted substantially in the horizontal plane. As in thethird embodiment, the aim of the driveshaft, as influenced by thedirectional rotation of azimuthal directional orientation means 35, isactively controlled by active azimuthal directional orientation controlmeans 96, illustrated here as a simple gear drive.

[0151] In this case the offset angle α is in the horizontal plane. Theamount of offset angle may be tailored to prevailing wind conditions; Inmoderate winds the offset angle α may be adjusted to provide maximumpower, maximizing the windflow to each rotor, by reducing the windshadow effect from one rotor to the next. In excessively strong winds,the offset angle α may be reduced, even to zero, placing the series ofrotors more in line with the wind, so that they tend to shield oneanother from the full force of the wind, preventing overspeed, andthereby limiting damage from high winds.

[0152] 8. Eighth Embodiment: Downwind, Self-Orienting HorizontalDriveshaft with Passively Determined Offset Angle α in the HorizontalPlane; FIG. 18:

[0153] In the eighth embodiment, like the seventh, the driveshaft 10 issubstantially horizontal, with the offset angle α being in thehorizontal plane. In this case, however, the offset angle α is passivelydetermined by a fluid reactive offset angle inducing means 94,illustrated as a simple fin, or paddle, attached to the azimuthaldirectional orientation means 35. This simple paddle, or fin, tends tobe blown downwind, causing the assembly to which it is attached,including the driveshaft 10, to become offset from the wind direction,to a point where the offset force is balanced by the counteracting forceof the downwind section of the driveshaft and its attached rotorsundergoing their natural, downwind, self-orienting, weathervane-likebehavior. The size and angle of the fin 94 are adjusted to providemaximum power, allowing each rotor to receive a substantial portion offresh wind, substantially undisturbed by upwind rotors.

[0154] 9. Ninth Embodiment: Streamlined, Aerodynamic Nacelle; FIG. 6:

[0155] The previous embodiments have shown the bearing support means 4as a simple tube, to convey the mechanical essence of the invention, thepossible simplicity of construction, and to show continuity withpreviously disclosed embodiments in the prior U.S. patent applicationSer. No. 09/881,511. In actual practice, a more aerodynamic streamlinednacelle 98 serves to reduce the interference of the bearing supportmeans 4, the load 6, and associated apparatus, with the wind. FIG. 6illustrates a more aerodynamic bearing support means 4, that, beingtapered at each end, serves as a nacelle, reducing aerodynamic drag andthereby reducing aerodynamic interference with the rotors. The nacelleshown also serves as the bearing support means 4, but couldalternatively comprise a simple fairing, within the scope of thisembodiment. In addition, a streamlined mounting pylon 97 serving aselevation angle control means 36, and at least partially serving asdownwind offset extension means 95, is also aerodynamically shaped, tofurther reduce wind drag and interference. This streamlined pylon 97 ismounted atop horizontally rotatable azimuthal directional orientationmeans 35.

[0156] 10. Tenth Embodiment: Horizontally Rotatable AzimuthalDirectional Orientation Means 35 Located Within Aerodynamic MountingPylon 97; FIGS. 1, 2, 3, 4:

[0157] In previous embodiments the horizontally rotatable azimuthaldirectional orientation means 35 is illustrated as a turntable-likeunit, to most effectively illustrate its function. In this embodiment,otherwise similar to the previous, ninth embodiment, this horizontallyrotatable azimuthal directional orientation means 35 comprises asubstantially vertical, cylindrical unit housed within theaerodynamically shaped mounting pylon 97. Such a vertical, cylindricalunit may fit neatly over the top of a vertical, substantiallycylindrical tower, as illustrated, and effectively serve as a pivotabout the vertical axis.

[0158]FIG. 1 is an oblique perspective side view.

[0159]FIG. 2 is a closeup of the streamlined nacelle 98.

[0160]FIG. 3 shows a version having two-bladed rotors, sequentiallyoffset by 90 degrees. Such a two-bladed rotor configuration may beequally applied to all embodiments disclosed herein. Any reasonablenumber of rotor blades are possible, within the scope of this invention,for the rotors of all embodiments disclosed herein.

[0161]FIG. 4 attempts to approximately illustrate the manner in whichthe offset angle α allows each rotor to encounter at least some freshwind substantially undisturbed by upwind rotors. In this respect, FIG. 4is applicable to all embodiments disclosed herein. Note that with theoffset angle in the vertical plane, with the driveshaft and attachedrotors tilted forward, the wind is deflected slightly downward by therotors.

[0162] 11. Eleventh Embodiment: Upper Section of Tower is Offset andRotates; FIG. 5:

[0163] In this passively aimed, downwind embodiment, the tower 90 issplit into two sections, an upper section and a lower one. The uppersection fits over the lower one and is free to coaxially rotatethereabout. This rotatable interface, which may include bearings forsmooth rotation, is essentially a pivot about the vertical axis, andcomprises the horizontally rotatable azimuthal directional orientationmeans 35. Above this interface, the tower diverts from the vertical,thereby comprising downwind offset extension means 95. Still further upthe tower, just before its supporting attachment to the cantileveredbearing means 5 housed within the aerodynamic nacelle 98, the towerbends further, with this final angle comprising elevation angle controlmeans 36. Since this upper section of the tower rotates with the winddirection, it may be aerodynamically shaped, or include a fairing means(not shown).

What is claimed is:
 1. A wind turbine, comprising: a series ofsubstantially horizontal axis type rotors attached in a substantiallycoaxial manner at spaced intervals along a driveshaft; said driveshaftaimed sufficiently parallel to the wind for the rotors to effectivelyharness the wind, but at an offset angle from the wind direction,sufficient to allow an admixture of fresh wind, substantiallyundisturbed by upwind rotors, to each rotor; said driveshaft held in arotationally free, cantilevered manner, by a cantilevered bearing meansfrom which it projects; wherein at least part of said driveshaftprojects from said cantilevered bearing means substantially toward thewind.
 2. The wind turbine of claim 1 wherein said cantilevered bearingmeans is disposed substantially midway along said driveshaft.
 3. Thewind turbine of claim 1, wherein said bearing means is disposedsufficiently toward one end of said driveshaft that the other end ofsaid driveshaft, with its attached rotors, is caused to be blownsubstantially downwind of said bearing means, so that said wind turbineis caused to become aimed substantially into the wind, in the manner ofa weathervane.
 4. The wind turbine of claim 2 wherein said bearing meansis supported by a downwind offset extension means, which serves toprovide an offset distance from said bearing means to a horizontallyrotatable azimuthal directional orientation means, about which saidextension means, said bearing means, and said driveshaft with attachedrotors are free to rotate as a unit in the horizontal plane, in themanner of a weathervane.
 5. The windmill of claim 1 further comprisingan active aiming mechanism, whereby the directional aim of saiddriveshaft may be determined.
 6. The wind turbine of claim 1 whereinsaid offset angle is in the vertical plane.
 7. The wind turbine of claim1 wherein said offset angle is in the horizontal plane.
 8. The windturbine of claim 1 wherein said offset angle is oblique.
 9. A windturbine comprising: a cantilevered bearing means; an upwind section of adriveshaft, projecting from one end of said cantilevered bearing means,supported thereby in a substantially rotationally free manner; a seriesof substantially horizontal axis rotors attached at spaced intervals tosaid upwind section of said driveshaft in a substantially coaxialmanner; wherein: the direction of projection of said driveshaft issufficiently parallel to the wind for said attached rotors toeffectively harness the wind and thereby cause rotation of said sectionof said driveshaft; the distance between said rotors is sufficient toallow an admixture of at least some fresh wind, substantiallyundisturbed by upwind rotors, to enter the wind stream passing througheach rotor.
 10. The wind turbine of claim 9, further comprising: adownwind section of said driveshaft, extending from the other end ofsaid cantilevered bearing means, supported thereby in a substantiallyrotationally free manner; a series of substantially horizontal axisrotors attached at spaced intervals to said downwind section of saiddriveshaft in a substantially coaxial manner;
 11. The wind turbine ofclaim 10, wherein said upwind section and said downwind section of saiddriveshaft are divided one from the other, the upwind section of saiddriveshaft driving one half of a load, and said downwind section drivingthe other half of the load in the opposite direction, so that the twohalves of the load are counterrotating, effectively substantiallydoubling the effective relative rate of rotation of the load.
 12. Thewind turbine of claim 9, wherein the direction of projection of saiddriveshaft is at an offset angle from the wind direction, sufficient toallow a substantial part of the disk swept by each rotor to encounter astream of air substantially undisturbed by upstream rotors.
 13. The windturbine of claim 10, wherein the direction of projection of saiddriveshaft is at an offset angle from the wind direction, sufficient toallow a substantial part of the disk swept by each rotor to encounter astream of air substantially undisturbed by upstream rotors.
 14. A windturbine, comprising: an elongate driveshaft; a plurality ofsubstantially horizontal axis type rotors; a cantilevered bearing means;a load; means for allowing a substantial portion of the disk swept byeach said rotor to encounter fresh wind, substantially undisturbed byupwind rotors; wherein: said driveshaft is supported in a rotationallyfree manner by said bearing means, projecting therefrom in two opposingdirections; said rotors are mounted to said driveshaft in asubstantially coaxial manner, at spaced intervals therealong; said loadis configured and disposed in a manner whereby it may be driven by therotation of said driveshaft; said driveshaft is disposed sufficientlyparallel to the wind that said attached rotors can be driven by the windto cause said shaft to rotate about its own longitudinal axis;
 15. Thewind turbine of claim 14, wherein said means for allowing a substantialportion of the disk swept by each said rotor to encounter fresh windcomprises: a sufficient distance between said rotors to allow asubstantial admixture of said fresh wind into the wind streamencountered by each said rotor.
 16. The wind turbine of claim 14,wherein said means for allowing a substantial portion of the disk sweptby each said rotor to encounter fresh wind comprises: an offset anglemeans that causes said driveshaft to be disposed at an offset angle fromthe exact wind direction.
 17. The wind turbine of claim 14, wherein saidmeans for allowing a substantial portion of the disk swept by each saidrotor to encounter fresh wind comprises: sufficient distance betweensaid rotors to allow a substantial admixture of said fresh wind into thewind stream encountered by each said rotor, and; an offset angle meansthat causes said driveshaft to be disposed at an offset angle from theexact wind direction.
 18. The wind turbine of claim 17, wherein saidoffset angle is in the vertical plane, as determined by an elevationangle control means.
 19. The wind turbine of claim 17, wherein saidoffset angle is in the horizontal plane.
 20. The wind turbine of claim17, wherein said offset angle is oblique.
 21. The wind turbine of claim17, further comprising: a horizontally rotatable azimuthal directionalorientation means; a downwind offset extension means; whereby: saiddownwind offset extension means allows said turbine to be blownsufficiently downwind of said horizontally rotatable azimuthaldirectional orientation means that said wind turbine is caused to bepassively aimed sufficiently parallel to the wind that said rotors arecaused thereby to rotate, rotating said shaft.
 22. The wind turbine ofclaim 21, wherein said downwind offset extension means comprises ahorizontally offset interface between said azimuthal directionalorientation means and said cantilevered bearing means.
 23. The windturbine of claim 21, wherein said downwind offset extension meanscomprises a difference in length between the downwind section of saiddriveshaft and the upwind section of said driveshaft.
 24. The windturbine of claim 21, wherein said downwind offset extension meanscomprises a preponderance of rotors on the downwind section of saiddriveshaft.
 25. The wind turbine of claim 21, wherein said downwindoffset extension means comprises a preponderance of aggregate distanceof downwind rotors over that of upwind rotors, from said azimuthaldirectional orientation means, giving said downwind rotors aperponderance of leverage as compared to that of said upwind rotors,sufficient that said downwind section is caused by the wind to be blownto a substantially downwind position, whatever the wind direction,thereby causing said upwind section of said driveshaft to be aimedsubstantially into the wind, making this turbine a passively aimedmachine, that is self aiming in the fashion of a weathervane.
 26. Thewind turbine of claim 21, wherein said downwind offset extension meanscomprises a preponderance of aggregate leverage of downwind rotors overthat of upwind rotors, from said azimuthal directional orientationmeans, sufficient that said downwind section is caused by the wind to beblown to a substantially downwind position, whatever the wind direction,thereby causing said upwind section of said driveshaft to be aimedsubstantially into the wind, making this turbine a passively aimedmachine, that is self aiming in the fashion of a weathervane.
 27. Thewind turbine of claim 26, wherein the upwind section of said driveshaftfurther comprises a counterweight means to balance against the forceexerted by said preponderance of aggregate leverage of downwind rotorsand said downwind section of driveshaft.